| 유동층 화학기상증착법으로 제조된 TRISO 피복입자의 ZrC 층 미세구조와 경도에 미치는 증착온도의 영향 |
| 고명진, 김대종, 김원주, 조문성1, 윤순길2, 박지연 |
한국원자력연구원 원자력재료개발부
1한국원자력연구원 차세대핵연료개발부
2충남대학교 재료공학과 |
| Effect of Deposition Temperature on Microstructure and Hardness of ZrC Coating Layers of TRISO-Coated Particles Fabricated by the FBCVD Method |
| Myung-Jin Ko, Daejong Kim, Weon-Ju Kim, Moon Sung Cho1, Soon Gil Yoon2, Ji Yeon Park |
Nuclear Materials Division, Korea Atomic Energy Research Institute
1HTGR Fuel Technology Development Division, Korea Atomic Energy Research Institute
2Department of Materials Science and Engineering, Chungnam National University |
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| ABSTRACT |
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Tristructural-isotropic (TRISO)-coated particles were fabricated by a fluidized-bed chemical vapor deposition (FBCVD) method for use in a very high temperature gas-cooled reactor (VHTR). ZrC as a constituent layer of TRISO coating layers was deposited by a chloride process using $ZrCl_4$ and $CH_4$ source gases in a temperature range of $1400^{circ}C$ and $1550^{circ}C$. The change in the microstructure of ZrC depending on the deposition temperature and its effect on the hardness were evaluated. As the deposition temperature increased to $1500^{circ}C$, the grain size of the ZrC increased and the hardness of the ZrC decreased according to the Hall-Petch relationship. However, at $1550^{circ}C$, the ZrC layer was highly non-stoichiometric and carbon-rich and did not obey the Hall-Petch relationship in spite of the decrease of the grain size. A considerable amount of pyrolytic carbon at the grain boundaries of the ZrC as well as coarse granular pyrolytic carbon were locally distributed in the ZrC layer deposited at $1550^{circ}C$. Therefore, the hardness decreased largely due to the formation of a large amount of pyrolytic carbon in the ZrC layer. |
| Key words:
TRISO coating, Zirconium carbide, Fluidized-bed chemical vapor deposition |
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